This invention relates generally to fluid translating units and more particularly to a compact fluid translating device and the use thereof in a fluid system.
Fluid translating units are well known in the art. They may be designed to function as a fluid pump or a fluid motor. Typically, in the axial piston units, they have a stationary housing having a fluid inlet port, a fluid outlet port, an internal rotating unit connected to an input/output shaft, a cam/swash plate and internal porting to meter the fluid flow therethrough. The rotating unit normally includes a rotating barrel having a plurality of piston assemblies slideably disposed therein in contact with the cam/swash plate. Due to the outer stationary housing, these known fluid translating units are normally somewhat bulky and require additional space when space may be very limited. Additionally, the known axial fluid translating units are limited, based at least in part on the piston assemblies, in their angular displacement. In many of the known designs, the input/output shaft is cantilevered and loads applied thereto tend to cause premature bearing failures. There are some fluid translating motors that rotate the outer portion of the motor at the same time that the translating unit is being rotated. These arrangements require, in most cases, the use of radial fluid translating units and have additional length due to the output shaft extending from both ends. One such example is set forth in U.S. Pat. No. 5,396,768 issued to Joshua Zulu on Mar. 14, 1995.
The present invention is directed to overcoming one or more of the problems set forth above.
In one aspect of the present invention, a fluid translating device is provided and comprises a stationary central shaft, first and second members, a camplate, a port plate, a plurality of pistons, and an outer input/output member. The stationary central shaft has first and second end portions and a center portion with a reference axis extending through the first, second, and center portions. The first member is securely connected to the first end portion of the stationary central shaft about the reference axis and has an end face and first and second inlet/outlet ports in communication with the end face thereof. The second member is securely connected to the second end portion of the stationary central shaft about the reference axis and has a face surface and a plurality of equally spaced blind bores defined therein about the reference axis and the plurality of blind bores extends from the face surface thereof parallel to the reference axis. The camplate is rotatably disposed about the reference axis of the stationary central shaft between the first and second members and has a first end face portion in abutting contact with the end face of the first member and a second end face portion angled with respect to the reference axis and has a recess defined therein. A face surface is disposed in the recess and the face surface therein is in communication with the first end face portion thereof. The port plate has a bearing assembly disposed thereabout and is located within the recess of the camplate. The port plate has first and second opposed faces and a plurality of equally spaced formed cavities defined therein about the reference axis between the first and second opposed faces. The port plate is positioned with the first opposed face thereof being in mating contact with the face surface of the recess in the camplate. Each piston of the plurality of pistons has first and second end portions with the first end portion being slideably disposed within the respective blind bores of the second member to define pressure chambers therein and the second end portion thereof is in contact with the other opposed face of the port plate. The outer input/output member is disposed about the camplate and the first and second members and the outer input/output member is secured to the camplate and rotatable about the first and second members.